Hobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gearHobs for double-circular-arc gear